1. Field of the Invention
This invention relates to a method of making a photoprocessing reference image control tool photograph and methods of converting image data, particularly to a method of making a photoprocessing reference image control tool photograph suitable for use in setting the exposure conditions and checking the development performance of an automatic printer or print processor capable of printing an image recorded onto photographic film (a silver halide photographic recording medium) on printing paper (a silver halide photographic recording medium) under automatically controlled exposure conditions and to methods of converting image data that utilize this method.
2. Description of the Related Art
The automatic printer and the automatic print processor (a printer with development processing capability) are devices for automatically printing images recorded using color negative film on color printing paper to obtain color prints (positive images). Proper development processing and proper setting of the automatic printer exposure conditions are essential for consistently obtaining high quality color prints. The automatic printer has a slope control feature that effects correction to make the density and color balance of the finished print the same irrespective of the negative image contrast (underexposure, proper exposure or overexposure). A type of control negative called an eyeball negative is generally used to adjust the slope control and set the exposure conditions. The eyeball negative is produced by effecting exposure to obtain a portion at the center corresponding to a negative obtained by photographing a round gray subject and a surrounding portion corresponding to a negative obtained by photographing a green subject.
The relationship with the photographed subject is indefinite with the eyeball negative, however, because only the portion corresponding to a negative obtained by photographing a round gray subject is imaged at the center portion. The eyeball negative is therefore hard to use.
In response to this situation, PCT Japanese Publication No. 5(1993)-506733 corresponding to WO92/15957 teaches a method of producing a second-generation camera original photoprocessing reference image control tool photograph that utilizes a transparency photograph digitally generated to represent the actual scene. This method photographs a first image including a preselected scene and subject onto a first photographic recording medium and photographs a second image representing photographic processing control data on a second photographic recording medium. It next converts the first and second images to first and second numerical images and stores them in the primary digital image datametric of a digital image database. It then digitally inserts the second numerical image into the first numerical image to generate composite digital image data and selectively adjusts one or more parameters of the composite image. Finally, it uses a digital output recording apparatus to record the composite image onto a photographic recording medium, photographs the composite image recorded onto the photographic recording medium and develops the obtained composite image photograph to obtain a photoprocessing reference image control tool photograph.
The photoprocessing reference image control tool photograph is used in the following manner to set the exposure conditions of a printer. First, photoprocessing reference image control tool photographs are produced in correspondence to the cases of overexposure, underexposure and proper-exposure photography. The produced tools are then used to form photoprocessing reference image control tool photograph images on light-sensitive material. At this time, the exposure conditions are set to give the gray portion of each photoprocessing reference image control tool photograph a prescribed density. Some fine adjustment of the exposure conditions may be necessary to obtain natural-looking flesh portions, however, because such portions may in some cases be rendered in the wrong density if the gray portion is given the prescribed density. The exposure conditions are stored in memory. At the time of printing, the exposure conditions are set based on the relationship between the overall density of the film and the density of the photoprocessing reference image control tool photographs. Printed images (prints) are made using these exposure conditions. The printed image obtained by this method exhibits proper density of the gray portions and the flesh portions. (The exposure condition settings are those in the case where image formation on the light-sensitive material was conducted using standard exposure conditions. In the case of a light-sensitive material exposed using conditions other than standard, such as by use of a nonstandard exposure light source, separate corrective adjustment is necessary.)
This prior art method photographs the second image with a camera and then converts it to a numerical image by photographic numerical conversion. This need to conduct two steps, image taking and numerical conversion, makes the image taking troublesome and time consuming. To overcome this inconvenience, Japanese Unexamined Patent Publication No. 9(1997)-15760 and Japanese Unexamined Patent Publication No. 9(1997)-15761, for example, teach methods that enable production of photoprocessing reference image control tool photographs simply and quickly by using computer graphics technology to produce photoprocessing reference images.
However, the methods taught by PCT Japanese Publication No. 5(1993)-506733(WO92/15957), Japanese Unexamined Patent Publication No. 9(1997)-15760 and Japanese Unexamined Patent Publication No. 9(1997)-15761 all obtain the final photoprocessing reference image control tool photograph by once recording a composite image of a first image and a second image onto an intermediate recording medium and then photocopying the intermediate recording medium carrying the composite image. This makes production of the photoprocessing reference image control tool photograph very troublesome. A considerably easier method would be to record the composite image onto the final silver halide photographic recording medium without once recording it onto an intermediate recording medium. However, when the composite image is recorded directly onto the final silver halide photographic recording medium, photographing of the original image has to be repeated for each different type of silver halide photographic recording medium. This is impractical in the actual production of prints.
This invention was accomplished in light of the foregoing problems and has as one of its objects to provide a method of making a photoprocessing reference image control tool photograph that enables simple production of a photoprocessing reference image control tool photograph without need to produce an intermediate recording medium. Another object of the invention is to provide methods of converting image data that utilize the method of making a photoprocessing reference image control tool photograph.
The method of making a photoprocessing reference image control tool photograph according to the invention includes:
step A of acquiring digital (F) image data representing an image of a preselected subject,
step B of acquiring first digital chart image data representing a color chart composed of multiple color patches using the same acquisition conditions as those used at the time of acquiring the digital image data,
step C of recording. an image of the color chart onto a silver halide photographic recording medium (F),
step D of converting the color chart image recorded onto the prescribed silver halide photographic recording medium (F) to second digital chart image data and determining a correspondence relationship defining correspondence of digital signal values of the patches between the first and second digital chart image data,
step E of converting the digital image data based on the correspondence relationship to obtain converted image data, and
step F of recording a converted image represented by the converted image data onto a silver halide photographic recording medium (G) of the same type as the silver halide photographic recording medium (F) to obtain a photoprocessing reference image control tool photograph.
Step A can be a step of acquiring the digital image data by photographing the subject with a digital image input device and step B can be a step of acquiring the first digital chart image data by photographing the color chart with a digital image input device of the same type.
Step A preferably includes a sub-step A1 of photographing the subject to record an image of the subject onto a first silver halide photographic recording medium and a sub-step A2 of using a device such as a scanner to read and convert the image of the subject recorded onto the first silver halide photographic recording medium to the digital image data and step B preferably includes a sub-step B1 of recording the color chart onto a second silver halide photographic recording medium of the same type as the first silver halide photographic recording medium and a sub-step B2 of using a device such as a scanner to read and convert the color chart image recorded onto the second silver halide photographic recording medium to the first digital chart image data.
The silver halide photographic recording medium (F) is the same type as the silver halide photographic recording medium (G) to be used for the final photoprocessing reference image control tool photograph and, in the case of obtaining the digital image data by recording an image of the subject onto the first silver halide photographic recording medium, can be of the same type as or a different type from the first silver halide photographic recording medium.
As the subject in step A there can be selected a person or other such typical subject frequently photographed by general photographers.
Step B acquires first digital image data representing a color chart using the same acquisition conditions as those used when acquiring the image of the subject. By xe2x80x9csame acquisition conditionsxe2x80x9d is meant that the image of the subject and the color chart are recorded onto the same type of silver halide photographic recording medium, that the exposure conditions are the same and that the photography is conducted using the same model of digital image input device. When the digital image data are obtained by recording the image of the subject onto the first silver halide photographic recording medium, the first silver halide photographic recording medium and the silver halide photographic recording medium (F) can be of the same type or of different types. The color chart preferably includes multiple neutral gray and color patches. ColorChecker, a product of Greta Macbeth, is an example of such a color chart.
xe2x80x9cSilver halide photographic recording media of the same typexe2x80x9d as termed with respect to the invention means recording media of, for example, identical speed, identical photosensitivity and identical coloration. Taking products of Fuji Photo Film Co., Ltd. as examples, film pairs considered to be different types include Fujicolor SUPER G ACE 400 and SUPER G ACE 100, Fujicolor SUPER G ACE 400 and Fujicolor REALA ACE, Fujichrome ASTIA 100 and Fujichrome PROVIA. Fujicolor SUPER G ACE 400 and Kodak GOLD 400 film (product of Eastman Kodak Company) are also different types.
Step D converts the color chart image recorded onto the silver halide photographic recording medium (F) into the second digital chart image data, samples a digital signal value from each color patch, identifies sampled signal pairs between the first and second digital chart image data and determines a correspondence relationship defining correspondence between these signal values. The form of expression of this correspondence relationship can be, but is not limited to, one-dimensional LUT(look up table), matrix, three-dimensional LUT(look up table) and combinations of these.
Step E converts the digital image data obtained in step A based on the correspondence relationship determined in step D to obtain converted image data. An image of the subject was recorded onto the first silver halide photographic recording medium in step A. In this case, if the first silver halide photographic recording medium and the silver halide photographic recording medium (F) are of the same type, no conversion is effected and the digital image data obtained in step A are used without modification to conduct the processing of step F.
Step F produces the final photoprocessing reference image control tool photograph by using a digital image output device such as a film recorder using a CRT (cathode ray tube) or a laser as a light source to record the converted image data obtained in step E on a silver halide photographic recording medium (G) of the same type as the silver halide photographic recording medium (F).
In the method of making a photoprocessing reference image control tool photograph according to this invention, both the silver halide photographic recording medium (F) and the silver halide photographic recording medium (G) of the same type are preferably color negative films or color reversal films. When first and second silver halide photographic recording media are used, both are preferably color negative films or color reversal films.
A first method of converting image data according to the invention includes:
step A of acquiring digital image data representing an image of a preselected subject,
step B of acquiring first digital chart image data representing a color chart composed of multiple color patches using the same acquisition conditions as those used at the time of acquiring the digital image data,
step C of recording an image of the color chart onto a silver halide photographic recording medium (F),
step D of converting the color chart image recorded onto the silver halide photographic recording medium (F) to second digital chart image data and determining a correspondence relationship defining correspondence of digital signal values of the patches between the first and second digital chart image data, and
step E of converting the digital image data based on the correspondence relationship to obtain converted image data.
A second method of converting image data according to the invention includes:
step A of acquiring digital image data representing an image of a preselected subject by photographing the subject using an exposure condition (E),
step B of acquiring first digital chart image data representing a color chart composed of multiple color patches by photographing the color chart using an exposure condition (F) the same as the exposure condition (E)
step C of acquiring second digital chart image data representing the color chart by photographing the color chart using an exposure condition (H) different from the prescribed exposure condition (E),
step D of determining a correspondence relationship defining correspondence of digital signal values of the patches between the first and second digital chart image data, and
step E of converting the digital image data based on the correspondence relationship to obtain converted image data.
In the method of making a photoprocessing reference image control tool photograph according to the invention, the first digital chart image data are acquired using the same acquisition conditions as those used to acquire the digital image data and an image of the color chart is recorded onto a silver halide photographic recording medium (F). Next, a correspondence relationship defining correspondence of the digital signal values of the color chart patches between the first digital chart image data and second color chart image data converted from the color chart recorded onto the silver halide photographic recording medium (F) is then determined. The digital image data are then converted into converted image data based on this correspondence relationship and the converted image data are recorded onto a silver halide photographic recording medium (G) of the same type as the silver halide photographic recording medium (F) to obtain a final photoprocessing reference image control tool photograph. This method of the invention can make the photoprocessing reference image control tool photograph without producing the intermediate recording medium required by the methods taught by PCT Japanese Publication No. 5(1993)-506733, Japanese Unexamined Patent Publication No. 9(1997)-15760 and Japanese Unexamined Patent Publication No. 9(1997)-15761. It therefore enables bother-free production of a photoprocessing reference image control tool photograph. Moreover, no need arises to photograph an original image every time there is a change in the acquisition conditions used to acquire the digital image data because the correspondence relationship defining correspondence between the acquisition conditions and the silver halide photographic recording medium (F) is determined beforehand. This makes it possible to produce photoprocessing reference image control tool photographs with no practical difficulty.
Like the invention method of making a photoprocessing reference image control,tool photograph, the first method of converting image data according to the invention determines a correspondence relationship defining correspondence of the digital signal values of the color chart patches between the first digital chart image data and second color chart image data and converts the digital image data based on the correspondence relationship to obtain converted image data. Digital image data identical with digital image data representing an image photographed on the silver halide photographic recording medium (F) can therefore be obtained merely by acquiring the digital image data, with no need to again photograph the subject on the silver halide photographic recording medium (F).
The second method of converting image data according to the invention photographs a subject using a exposure condition (E) and acquires digital image data representing the image of the subject, photographs a color chart using the same exposure condition (F) and acquires first digital chart image data representing the color chart image, and records the color chart onto a silver halide photographic recording medium (F) using an exposure condition (H) different from that used at the time of acquiring the digital image data. It next determines a correspondence relationship defining correspondence of digital signal values of the color chart patches between the first digital chart image data and second color chart image data obtained by converting the color chart recorded onto the silver halide photographic recording medium (F). It then converts the digital image data based on the correspondence relationship to obtain converted image data. Therefore, if the photographed image of the subject should happen to be underexposed, for example, digital image data representing a properly exposed image can nevertheless be obtained as converted image data, with no need to photograph the same subject a second time, because the color chart image recorded onto the silver halide photographic recording medium (F) with proper exposure is used to determine the correspondence relationship for the data conversion.